The present invention relates to an apparatus for automatically bending a band-shaped work made of metal or the like into a desired form, and also relates to a device for making a notch mark on a longitudinal edge of such a work.
Referring to FIG. 20, there is shown a known punching die 202 consisting of a base plate 201 made of wood and a track-shaped band knife 200 embedded so as to project from one surface of the base plate 201. The punching die 202 is used to punch a plate or sheet of various materials (e.g., plywood, leather, paper, cloth, and plastic board) into a desired form or form a cut line on such a plate or sheet with a desired form. That is, the punching die 202 is lowered onto such a plate or sheet to effect punching or cutting.
Such a band knife is formed by bending a linear band-shaped work into a desired shape by using a bending apparatus, an example of which is disclosed in Japanese Patent Laid-open Publication No. 63-309328. The prior art bending apparatus will be described with reference to FIG. 21.
As shown in FIG. 21, a band-shaped work w is fed in a longitudinal direction thereof by a pair of feed rollers a and pass through a fixed holder b along a slit formed therein to project from an outlet of the slit. A bending member c is movably provided in the vicinity of the outlet of the slit of the holder b so as to be moved along an arcuate locus A--A. The bending member c is mounted inside of an annular gear, for example, adapted to be driven by a motor. Accordingly, when the annular gear is driven by the motor, the bending member c is moved with a given stroke H along the arcuate locus A--A to press a portion P.sub.1 of the work w against a forming edge d of the holder b, thereby bending the work w at the portion P.sub.1 at a desired angle. Thereafter, the bending member c is returned to an original position, and the work w is advanced a predetermined distance D by the feed rollers a. Then, the bending member c is driven again to press a portion P.sub.2 of the work w in the same manner as the above to thereby bend the work w at the portion P.sub.2. Subsequently, such a bending operation is similarly repeated to obtain an approximately arcuate bent portion of the work w, for example.
However, the prior art bending apparatus has the following drawbacks. First, in the case of replacing the bending member c, the replacement is hard or very troublesome. The replacement of the bending member c is necessary in the case of using another bending member having a bending point different in shape from that of the bending member c in accordance with a shape of bend of the work w, or in the case of wearing or breaking of the bending member c. As the bending member c is fixed to the inside of an annular rotating body in general, it is necessary to disassemble a rotary mechanism, so as to replace the bending member c, thus requiring a troublesome work. Secondly, the bending member c is retained to the rotating body so as to be reciprocated near the front end of the holder b. However, since it is necessary to mount the rotating body so that it does not interfere with the holder b, thus requiring a special design to cause a complicated structure.
Further, in some cases, the band-shaped work is marked on a longitudinal edge thereof to indicate a reference position for an after-working. That is, in the case of punching the work after bending it with use of the bending apparatus or in the case of manually bending the work into a special shape difficult to obtain with use of the bending apparatus, such a punching or manual bending operation is performed on the basis of the mark after the bending operation by the automatic bending apparatus. The mark may be made by applying a paint or the like to the work. In this case, however, there is a possibility that the mark will disappear before the after-working or a position accuracy of the mark will be insufficient.